The opinion that it is impossible to make moral judgments about other people is sufficiently widespread amongst Christians to be worth attacking. It is of course a Christian doctrine that it is hardly ever my business to pass adverse moral judgments on people, but that is an entirely different matter. It is Christian teaching that I am very rarely justified in killing a man by shooting him with a gun, but we ought not to confuse this with the theory that it is impossible to kill a man by shooting him with a gun. In practice the latter theory will lead to a whole lot of death; similarly the theory that moral judgments are impossible leads to a whole lot of slander.

The theory is that while we can judge the behaviour of a man and say whether his external actions are good ones or bad ones, we cannot penetrate to his soul to see if he himself is good or bad. I can say that Peter did something that was ‘objectively’ or ‘materially’ wrong, but only God can say whether Peter was ‘subjectively’ or ‘formally’ committing a sin.